The present invention relates to a feeding device of an automatic sewing arrangement for producing a stitch contour in a workpiece according to a predetermined program. A linkage system installed with a control disc and a workpiece clamping plate operates upon a workpiece as a needle of a sewing head performs the stitching. In particular, a new feeding device installed with a linear drive, makes it possible to displace the workpiece relatively with respect to the linkage system.
Feeding devices of such types are known from the German laid-open DE-OS No. 30 00 831 and also from German Pat. DE-PS No. 27 33 397. These are installed essentially with a linkage system having a parallelogram-shaped configuration, in which two levers operating upon a stationary pivot point cooperate by cam followers with two grooves of a control disc. As the control disc is rotated for one revolution, the linkage system will be driven in a two-dimensional preset movement as controlled by the cams of the control disc. Due to their simple construction, such feeding devices operate reliably and are well-proven in the field. Furthermore, by simply exchanging the control disc, another program having a differently shaped switch contour may be achieved.
With such feeding devices the work area, i.e. the maximum of distances the workpiece holder is capable to be moved, is limited by the size of the linkage system. Depending on the application, it may happen that the work area of such a feeding device is not large enough as to sew a certain stitch program in a workpiece.
Accordingly, it is a main object of the present invention to create a feeding device of the aforesaid type so as to achieve an enlargement of the work area of the workpiece holder in a constructive manner.
Another object of the invention is to provide a feeding device with an extended work area and with control elements which make possible an automatic sewing process, in which the sewing process is automatically interrupted, the workpiece holder displaced, and the sewing process restarted again.
It is a further object of the present invention to provide a feeding device of the aforesaid type with a drive mechanism which is simple in construction and reliable in operation.